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Introduction to Computer Science
by Kai-Lung Hua
Chapter 0:Introduction
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Chapter 0: Introduction
• 0.1 The Role of Algorithms• 0.2 The Origins of Computing Machines• 0.3 The Science of Algorithms• 0.4 Abstraction• 0.5 An Outline of Our Study• 0.6 Social Repercussions
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Terminology
• Algorithm: A set of steps that defines how a task is performed
• Program: A representation of an algorithm• Programming: The process of developing
a program• Software: Programs and algorithms• Hardware: Equipment
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Figure 0.1 An algorithm for a magic trick
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History of Algorithms
• The study of algorithms was originally a subject in mathematics.
• Early examples of algorithms– Long division algorithm– Euclidean Algorithm
• Gödel's Incompleteness Theorem: Some problems cannot be solved by algorithms.
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Figure 0.2 The Euclidean algorithm
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Origins of Computing Machines
• Early computing devices– Abacus: positions of beads represent numbers– Gear-based machines (1600s-1800s)
• Positions of gears represent numbers• Blaise Pascal, Wilhelm Leibniz, Charles Babbage
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Figure 0.3 An Abacus
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Early Data Storage
• Punched cards– First used in Jacquard Loom (1801) to store
patterns for weaving cloth– Storage of programs in Babbage’s Analytical
Engine– Popular through the 1970’s
• Gear positions
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Early Computers
• Based on mechanical relays– 1940: Stibitz at Bell Laboratories– 1944: Mark I: Howard Aiken and IBM at Harvard
• Based on vacuum tubes– 1937-1941: Atanasoff-Berry at Iowa State– 1940s: Colossus: secret German code-breaker– 1940s: ENIAC: Mauchly & Eckert at U. of Penn.
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Figure 0.4 The Mark I computer
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Personal Computers
– First used by hobbyists– IBM introduced the PC in 1981.
• Accepted by business• Became the standard hardware design for most
desktop computers• Most PCs use software from Microsoft
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Computer Science
• The science of algorithms• Draws from other subjects, including
– Mathematics– Engineering– Psychology– Business Administration– Psychology
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Central Questions of Computer Science
• Which problems can be solved by algorithmic processes?
• How can algorithm discovery be made easier?
• How can techniques of representing and communicating algorithms be improved?
• How can characteristics of different algorithms be analyzed and compared?
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Central Questions of Computer Science (continued)
• How can algorithms be used to manipulate information?
• How can algorithms be applied to produce intelligent behavior?
• How does the application of algorithms affect society?
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Figure 0.5 The central role of algorithms in computer science
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Abstraction
• Abstraction: The distinction between the external properties of an entity and the details of the entity’s internal composition
• Abstract tool: A “component” that can be used without concern for the component’s internal properties
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Outline of Our Study
• Chapter 1: Data Storage• Chapter 2: Data Manipulation• Chapter 3: Operating Systems• Chapter 4: Networks and the Internet• Chapter 5: Algorithms• Chapter 6: Programming Languages
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Outline of Our Study (continued)
• Chapter 7: Software Engineering• Chapter 8: Data Abstractions• Chapter 9: Database Systems• Chapter 10: Computer Graphics• Chapter 11: Artificial Intelligence• Chapter 12: Theory of Computation
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Social Repercussions
• Advances in computer science raise new questions.– In law: Questions of rights and liabilities– In government: Questions of regulation– In the work place: Questions of
professionalism– In society: Questions of social behavior
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Ethical Theories
• Consequence based:
What leads to the greatest benefit?• Duty based:
What are my intrinsic obligations?• Contract based:
What contracts must I honor?• Character based:
Who do I want to be?